Caltech News tagged with "Watson_Lecture"http://www.caltech.edu/news/tag/Watson_Lecture/rss.xml
enA Molecular Arms Race: The Immune System Versus HIVhttp://www.caltech.edu/news/molecular-arms-race-immune-system-versus-hiv-46076
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/Watson-Lecture-Bjorkman-02-NEWS-WEB.jpeg?itok=rYmqEfW6" alt="" /><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Yunji Wu/Caltech</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><em>It is now more than 30 years after the first AIDS epidemic, and an effective vaccine against HIV does not yet exist—partly because the virus quickly mutates to evade the vaccine's antibodies. </em><em>On Wednesday, April 1, at 8 p.m. in Caltech's Beckman Auditorium, </em><em>Pamela J. Bjorkman, Caltech's </em><em>Max Delbrück Professor of Biology and an investigator with the Howard Hughes Medical Institute, will describe ways to neutralize </em><em>that mutational advantage. </em><em>Admission is free.</em></p><p> </p><p><strong>What do you do?</strong></p><p>We are structural biologists who use various imaging techniques to look at biological macromolecules and assemblies, sometimes in purified forms and sometimes in tissues. For example, we study HIV proteins alone, on viruses, and on viruses in tissues during an infection. Utilizing high-resolution structures of individual proteins, we are trying to apply our knowledge of the chemistry of protein-protein interactions to understanding what makes some antibodies produced by HIV-infected people good at neutralizing viruses and other antibodies less effective. We then try to reengineer good antibodies to make them even better in hopes that they could be used therapeutically to prevent or treat HIV infection.</p><p> </p><p><strong>What's the neatest thing about what you do?</strong></p><p>Using imaging techniques such as X-ray crystallography and electron microscopy, we can visualize structures in three dimensions, sometimes even localizing all of the atoms in a protein structure. This feels a bit like spying on nature—forcing her to reveal secrets that we can hopefully use to combat HIV/AIDS.</p><p> </p><p><strong>How did you get into this line of work?</strong></p><p>I was hooked after taking chemistry in high school. I knew then that I wanted to use chemistry to understand biology. I became interested in HIV about 10 years ago when I started teaching the Caltech freshman biology class and used HIV as a model system to understand basic principles of biology, especially evolution. HIV is an amazing example of successful evolution against which the human immune system loses, but I hope that we can win the war against HIV through a fundamental understanding of how it works.</p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U site</em></strong></a><strong><em>.</em></strong></p></div></div></div>Thu, 26 Mar 2015 00:50:38 +0000dsmith46076 at http://www.caltech.eduHow the Brain Learns from the Past and Makes Good Decisions for the Future: A Tour of Neural Reinforcement Learninghttp://www.caltech.edu/news/how-brain-learns-past-and-makes-good-decisions-future-tour-neural-reinforcement-learning-45565
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/ODoherty-WatsonLecture-NEWS-WEB.jpeg?itok=nYDDd7At" alt="fMRI scans of brain regions involved in value judgements" title="fMRI scans of brain regions involved in value judgements" /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Several areas of the brain are activated in the process of making value judgements, as these fMRI scans show.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: John O&#039;Doherty/Caltech</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><em>It is often said that people who do not learn from history are doomed to repeat it. Not being one of those people requires a network of different brain regions to work in concert. On Wednesday, February 4 at 8 p.m. in Caltech's Beckman Auditorium, John P. O'Doherty, professor of psychology and director of the Caltech Brain Imaging Center, will discuss our current understanding of how we learn from experience. Admission is free.</em></p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I study how we learn from experience. Humans and other animals have to make decisions all the time to maximize their benefits and minimize danger. These decisions range from what I should have for dinner or should I cross the road—which could have life-changing consequences if I'm wrong—to the selection of a life partner. I don't claim that "Who should I marry?" is equivalent to "Carrots or Brussels sprouts?" but we do think that many decisions share certain commonalities. So we look at very simple tasks that give us a window into how the brain solves problems to maximize future rewards.</p><p>We study brain activity by putting your head in an fMRI scanner. "MRI" stands for magnetic resonance imaging, and you've probably had one if you've had a sports injury. The "f" stands for "functional," and an fMRI scan detects changes in the oxygenation levels in the blood. If a certain part of the brain is active, its oxygen supply increases. We map those increases onto the brain's anatomy in 3-D while our volunteers perform some task that involves learning.</p><p>A task might be playing virtual slot machines. You have a choice of three machines, and we tell you one machine pays better than the others. So you choose one, press the button, and get instant feedback—you win or you lose. As you try to work out which machine is better, we monitor the patterns of activity in various parts of your brain. One of our goals is to find the part of the brain that represents the <em>experienced</em> value of the things we meet in the world—how good it feels to win, or how bad to lose.</p><p>We're also interested in how the brain changes its expectations. As you play the machines, you're constantly revising your estimate of which machine is better. We have computational models that we think represent how the brain internalizes feedback, and we're trying to find brain areas where the activity matches those models.</p><p>We think that understanding the neural circuits and computations that underpin our decision-making capacity may shed some light on certain psychiatric disorders, such as obsessive-compulsive disorder, depression, and addiction. On some level, all of these can be seen as decision-making gone wrong. Addiction, for example, involves a choice—voluntary or otherwise—to engage in a certain pattern of behavior.</p><p> </p><p><strong>Q: Setting aside clinical disorders, why do people make garden-variety bad decisions? What leads us to cross a busy road and almost not make it?</strong></p><p>A: First, it's important to emphasize that humans are collectively pretty good at making decisions. That's why we've been so successful as a species. But there could be all sorts of reasons why an individual might make a poor decision. For example, you might underestimate how fast the traffic is moving.</p><p>My lab is particularly interested in how two distinct decision-making mechanisms may interact to produce bad outcomes. One mechanism is "goal-directed," in which you evaluate the consequences of your action in light of the goal you're pursuing. This requires a lot of mental energy. In contrast, "habit-controlled" decision-making is basically stimulus-response—you react to some cue from the environment. Habits can be very beneficial, because you can execute them quickly without thinking deeply. Once you learn to ride a bicycle, for example, you don't have to concentrate on keeping your balance. It becomes routine, and you can focus your mental energy on other things. Poor decisions can result when the habit system drives your behavior when you really should be solving things in a goal-directed manner. This may be how addiction becomes compulsive. The goal-directed system says, "I don't want to take this drug any more," but the habitual system overrides it.</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: Even as a kid I was interested in science and its unsolved mysteries. I was actually keen on astronomy as a teenager and really considered going in that direction. Then I started getting interested in how computers work, which led me to start wondering about how the most complex computer that we know of works, namely our brain. So I basically had a career choice between studying the universe or studying the brain, which are probably the world's two greatest outstanding mysteries. I decided to take my chances on the brain.</p><p>At the time, the field of cognitive neuroscience was based on the paradigm that the brain is like a digital computer, and brain processes were modeled in essentially in the same way. There were lots of studies of memory, such as recalling lists of words, but very little was known about how the brain assigns a greater value to some things than others. But it's a really fundamental question, because the ability to work out whether something is good or bad—and to maximize behaviors that lead to good things and avoid bad things—is <em>critical</em> for survival. Digital computers typically don't make value judgments of that sort unless they are programmed to do so. So that's what excited me, trying to unlock how it is that the brain assigns value to things in the world.</p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at <a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541">Caltech's iTunes U site</a>.</em></strong></p></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://olab.caltech.edu/home.html" class="pr-link">The O'Doherty Lab's Website</a></div></div></div>Mon, 02 Feb 2015 19:21:38 +0000dsmith45565 at http://www.caltech.eduSize Matters: The Importance of Building Small Thingshttp://www.caltech.edu/news/size-matters-importance-building-small-things-45374
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/JGreer-Octa_15x12um-NEWS-WEB.jpeg?itok=L6HGncgu" alt="A fractal nanotruss made in Greer&amp;#039;s lab." title="A fractal nanotruss made in Greer&amp;#039;s lab." /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">A fractal nanotruss made in Greer&#039;s lab.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Lucas Meza, Greer lab/Caltech</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><em>Strong materials, such as concrete, are usually heavy, and lightweight materials, such as rubber (for latex gloves) and paper, are usually weak and susceptible to tearing and damage. Julia R. Greer, professor of materials science and mechanics in Caltech's Division of Engineering and Applied Science, is helping to break that linkage. In Caltech's Beckman Auditorium at 8 p.m. on Wednesday, January 21, Greer will explain how we can give ordinary materials superpowers. Admission is free.</em></p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I'm a materials scientist, and I work with materials whose dimensions are at the nanoscale. A nanometer is one-billionth of a meter, or about one-hundred-thousandth the diameter of a hair. At those dimensions, ordinary materials such as metals, ceramics, and glasses take on properties quite unlike their bulk-scale counterparts. Many materials become 10 or more times stronger. Some become damage-tolerant. Glass shatters very easily in our world, for example, but at the nanoscale, some glasses become deformable and less breakable. We're trying to harness these so-called size effects to create "meta-materials" that display these properties at scales we can see.</p><p>We can fabricate essentially any structure we like with the help of a special instrument that is like a tabletop microprinter, but uses laser pulses to "write" a three-dimensional structure into a tiny droplet of a polymer. The laser "sets" the polymer into our three-dimensional design, creating a minuscule plastic scaffold. We rinse away the unset polymer and put our scaffold in another machine that essentially wraps it in a very thin, nanometers-thick ribbon of the stuff we're actually interested in—a metal, a semiconductor, or a biocompatible material. Then we get rid of the plastic, leaving just the interwoven hollow tubular structure. The final structure is hollow, and it weighs <em>nothing</em>. It's 99.9 percent air.</p><p>We can even make structures nested within other structures. We recently started making hierarchical nanotrusses—trusses built from smaller trusses, like a fractal.</p><p> </p><p><strong>Q: How big can you make these things, and where might that lead us?</strong></p><p>A: Right now, most of them are about 100 by 100 by 100 microns cubed. A micron is a millionth of a meter, so that is very small. And the unit cells, the individual building blocks, are very, <em>very</em> small—a few microns each. I recently asked my graduate students to create a demo big enough to be visible, so I could show it at seminars. They wrote me an object about 6 millimeters by 6 millimeters by about 100 microns tall. It took them about a week just to write the polymer, never mind the ribbon deposition and all the other steps.</p><p>The demo piece looks like a little white square from the top, until you hold it up to the light. Then a rainbow of colors play across its surface, and it looks like a fine opal. That's because the nanolattices and the opals are both photonic crystals, which means that their unit cells are the right size to interact with light. Synthetic three-dimensional photonic crystals are relatively hard to make, but they could be extremely useful as high-speed switches for fiber-optic networks.</p><p>Our goal is to figure out a way to mass produce nanostructures that are big enough to see. The possibilities are endless. You could make a soft contact lens that can't be torn, for example. Or a very lightweight, very safe biocompatible material that could go into someone's body as a scaffold on which to grow cells. Or you could use semiconductors to build 3-D logic circuits. We're working with Assistant Professor of Applied Physics and Materials Science Andrei Faraon [BS '04] to try to figure out how to simultaneously write a whole bunch of things that are all 1 centimeter by 1 centimeter.</p><p> </p><p><strong>Q: How did you get into this line of work? What got you started?</strong></p><p>A: When I first got to Caltech, I was working on metallic nanopillars. That was my bread and butter. Nanopillars are about 50 nanometers to 1 micron in diameter, and about three times taller than their width. They were what we used to demonstrate, for example, that smaller becomes stronger—the pillars were stronger than the bulk metal by an order of magnitude, which is nothing to laugh at.</p><p>Nanopillars are awesome, but you can't build anything out of them. And so I always wondered if I could use something like them as nano-LEGOs and construct larger objects, like a nano-Eiffel Tower. The question I asked myself was if each individual component had that very, very high strength, would the whole structure be incredibly strong? That was always in the back of my mind. Then I met some people at DARPA (<em>Defense Advanced </em><em style="line-height: 1.538em;">Research Projects Agency</em><span style="line-height: 1.538em;">) at HRL (formerly Hughes Research Laboratories) who were interested in some similar questions, specifically about using architecture in material design. My HRL colleagues were making microscale structures called micro-trusses, so we started a very successful DARPA-funded collaboration to make even smaller trusses with unit cells in the micron range. These structures were still far too big for my purposes, but they brought this work closer to reality. </span></p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U site</em></strong></a><strong><em>.</em></strong></p></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://www.jrgreer.caltech.edu/home.php" class="pr-link">The Greer Lab's Website</a></div></div></div>Wed, 21 Jan 2015 17:08:45 +0000dsmith45374 at http://www.caltech.eduHow Do You Make a Greasy Protein?http://www.caltech.edu/news/how-do-you-make-greasy-protein-45153
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/ClemonsLab_8178-NEWS-WEB.jpeg?itok=hg1v0BTO" alt="Caltech Professor of Biochemistry Bil Clemons" title="Caltech Professor of Biochemistry Bil Clemons" /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Caltech Professor of Biochemistry Bil Clemons.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Van Urfalian/Caltech Office of Strategic Communications</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><em style="line-height: 1.538em;">Every cell is encapsulated and protected by a thin membrane made of greasy molecules called lipids. Assemblies of equally greasy protein molecules span the membrane, forming passageways that control the flow of signaling molecules that, in turn, direct the cell's activities. Because of these proteins' key role in cell-to-cell communication, they have become a prime target for drug design. Professor of Biochemistry Bil Clemons is among those working out the structures of these proteins and, more fundamentally, the biological processes behind them. Clemons will discuss how cells assemble these proteins, and how they deliver them to the membrane, a</em><em style="line-height: 1.538em;">t 8 p.m. on Wednesday, January 7, in Caltech's Beckman Auditorium</em><em style="line-height: 1.538em;">. Admission is free.</em></p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I am nominally a structural biologist, but I'm really a crystallographer. We purify a protein in solution and then try to crystallize it, which is really, really hard. When we succeed, we make X-ray diffraction patterns of the crystals and work backwards from those patterns to calculate the precise position of every atom. This allows us to make a blueprint for the molecule, and the blueprint helps us understand how the molecule does what it does. That's my group's real interest—figuring out the biological mechanisms that underlie how a protein works. We want to understand, on a molecular level, the processes by which these proteins are targeted and inserted into the membrane.</p><p>Proteins are long chains of amino acids that assume very specific three-dimensional shapes, or conformations. The proteins we work on contain hundreds of amino acids and thousands of individual atoms. These proteins interact with other molecules as they do their jobs. When they do, their conformations change, so a large part of our work is trying to understand all these different interactions and motions.</p><p>A crystal contains millions of copies of the same molecule held in <em>exactly</em> one conformation, so in that sense, a crystal structure is just one snapshot of a series of biological motions. Eventually we'd like to make movies of all the conformational changes that occur during these interactions—or at least render the important frames. It's almost like producing a cheap cartoon, where the lead animator draws a few key cels, and the rest is filled in later.</p><p> </p><p><strong>Q: What do you get from a crystal structure?</strong></p><p>A: We get the first glimpse of how something works. Every crystal structure provides a huge amount of information. The beauty of structural biology is that we get to be the first people to peek under the hood of a protein and draw a three-dimensional map of what we see. Science is vast, and most people work in very narrow fields, doing mechanistic studies and drug discovery and all sorts of things. Structural biologists create the platform for everyone else's studies.</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: Well, I'd like to say it was a series of happy accidents. I've always been passionate about science. In my heart, I think I was born a scientist. I always wanted to know how everything worked, and biochemistry fascinated me. There was so much complexity—so many ways to ask questions.</p><p>At Virginia Tech, I was lucky enough to have an undergraduate adviser, Walt Niehaus, who encouraged me to do research in his group. There was really no looking back after that. I just thought, "Wow. This is really fun. I like doing this." Meanwhile, I was paying my way through school. My senior year I was the student manager of one of the food-service facilities. I was working nearly 40 hours a week managing 40 employees plus spending another 20 hours in the lab and 20 hours in school. I wasn't able to look past that to what my future might be, but Walt pushed me to apply for grad school. It was eye-opening the first time he suggested I could do this for a living.</p><p>Walt's research was in basic biochemistry. There weren't any structural biologists at Virginia Tech at the time, but the Howard Hughes Medical Institute sent us a booklet with stereo pictures of protein structures. I thought, "You've got to be kidding me. We can look at these things in 3-D?" It blew my mind. So I went to grad school at the University of Utah to be a crystallographer, and I earned my PhD working on the molecular machinery responsible for making proteins. Then I did my postdoctoral work at Harvard Med, trying to understand the complex process of getting greasy membrane proteins into cell membranes. We solved the structure of an important piece of the puzzle there, and now that I'm at Caltech, which has major strengths in X-ray crystallography, we're filling in the details of the bigger picture.</p><p> </p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U site</em></strong></a><strong><em>.</em></strong></p></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://clemonslab.caltech.edu/" class="pr-link">The Clemons Laboratory's Website</a></div></div></div>Mon, 05 Jan 2015 19:49:09 +0000dsmith45153 at http://www.caltech.eduControlling Light on a Chip at the Single-Photon Levelhttp://www.caltech.edu/news/controlling-light-chip-single-photon-level-45084
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/setup.jpeg?itok=xADQsVho" alt="An optical bench in the Faraon lab." title="An optical bench in the Faraon lab." /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">The properties of nanoscale photonic devices are measured with elaborate optical apparatus.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Andrei Faraon/Caltech</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Integrating optics and electronics into systems such as fiber-optic data links has revolutionized how we transmit information. A second revolution awaits as researchers seek to develop chips in which individual atoms control the movement of light within the chip through optical "wires," and photons could replace electrons as the vehicle for performing computations. Andrei Faraon (BS '04), an assistant professor of applied physics and materials science in the Division of Engineering and Applied Science, presents a preview of this revolution at 8 p.m. on Wednesday, December 17, in Caltech's Beckman Auditorium. Admission is free.</p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: My field is nanophotonics, which means that I build ultrasmall devices to control light. Electronic devices use silicon chips to control the flow of electrical charge and to store it. We're trying to do the same thing with light, using single atoms or small ensembles of atoms that act like the transistors in electronic circuits. We're building devices out of complex oxides that are similar to glass, or to quartz, but contain atoms called lanthanides that have very interesting optical properties. Lanthanide atoms can absorb light and then release it on demand at some later time. So we're making a memory device. We want to take a single photon, put it in this device, and then push a button and release that photon back into a larger optical circuit.</p><p>These devices look like the world's smallest Toblerone bars, except that each tiny triangle is attached to its neighbors at the tip instead of the base. Each bar is about ten microns long, which is about the diameter of a red blood cell, and we make them using techniques similar to those used to make computer chips. The only difference is that we're not using silicon, but these complex oxides containing lanthanide atoms.</p><p>In order to use these devices, we would have them connected to one another by on-chip optical waveguides, or to a larger system by optical fibers. The signal would come in through the fiber, get stored in our Toblerone bar for a while, and then be released back into the fiber at the appropriate time. We dream of someday having billions of components on the same chip, but even one bit of optical memory can be useful.</p><p> </p><p><strong>Q: What would you use a one-bit memory for?</strong></p><p>A: It can be used in systems that transmit information with absolute security by what's called quantum communication. You can create an absolutely secure cryptographic key by sending a sequence of single photons, one at a time. Then you use the key to encrypt your data, which you can now send openly over the Internet. The systems that generate these keys over long distances are based on you sending a series of single photons from point A to point C, and a recipient sends another series from point B to point C. At point C you perform an operation on the photons, you combine them in some way, and that is used to establish the key.</p><p>However, optical fibers are not 100 percent efficient, especially over long distances. When you transmit photons through hundreds of kilometers of cable, some of them are going to get absorbed by the fiber. This isn't a big problem when each bit of information is encoded in a big pulse of light, but quantum communication depends on being able to interfere two paired single photons with each other. Many times when the photon from point A arrives at point C, you will have to store it until the photon from point B comes in. It might take a few tries before the second photon arrives, and until then the other one just waits for it.</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: When I was an undergraduate here, I really liked quantum physics. But I also had a passion for doing things that have some applications, so I went into applied physics for my PhD at Stanford. Transmitting information via cryptographic keys is one of the applications of quantum physics, so I got into this field for my PhD, and continued it during my postdoc at HP Laboratories, and now as a faculty member here.</p><p> </p><p><strong>Q: Bonus question: What's it like coming back as a professor after having been here as a student?</strong></p><p>A: It feels great. Coming back to Caltech is a privilege. As a faculty member you have the satisfaction of working with all these extremely smart kids. And my wife [Assistant Professor of Biology Viviana Gradinaru (BS '05)] and I go to many undergraduate events where we connect with the students, so it feels good.</p><p> </p><p style="margin-left: 40px;"><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><em>Caltech's iTunes U</em></a><em> site.</em></p><p> </p></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://photonics.caltech.edu/" class="pr-link">The Faraon lab's website</a></div></div></div>Mon, 15 Dec 2014 17:45:06 +0000dsmith45084 at http://www.caltech.eduPhotosynthesis: A Planetary Revolutionhttp://www.caltech.edu/news/photosynthesis-planetary-revolution-44508
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/WFischer-WatsonLecture-Homepage-NEWS-WEB.jpeg?itok=98gjuLat" alt="Sun shining through a leaf" title="Sun shining through a leaf" /><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Shutterstock</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><em>Two and a half billion years ago, single-celled organisms called cyanobacteria harnessed sunlight to split water molecules, producing energy to power their cells and releasing oxygen into an atmosphere that had previously had none. These early environmental engineers are responsible for the life we see around us today, and much more besides.</em></p><p><em>At 8:00 p.m. on <a href="/content/woodward-fischer-photosynthesis-planetary-revolution">Wednesday, November 19, in Caltech's Beckman Auditorium</a>, Professor of Geobiology Woodward "Woody" Fischer will describe how they transformed the planet. Admission is free.</em></p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I'm a geobiologist of the historical variety. I'm trying to understand both how the earth works, and why it works that way. The whys are hard, because you can't redo this planetary experiment. You have to create clever ways to work backward from what you can observe to answer the question you've posed.</p><p>When you boil down the earth's history, there are maybe a half-dozen singularities—fundamental changes in how our planet and the life on it interact. Photosynthetic cyanobacteria reengineered the planet. Photosynthesis led to two more singularities—plants and animals appeared. The remaining singularities are mass extinctions as a result of something happening to the global environment, and photosynthesis likely caused one of those as well. Oxygen can be highly toxic because it's so reactive. It chews up your DNA, and it binds to the metal compounds that cells use to shuttle electrons around. Any microbes that couldn't cope with this new pollutant died off, or were forced to hide in oxygen-depleted environments.</p><p>Atmospheric oxygen resulted from a change to a microbe's metabolism that evolved <em>once</em>, at a specific time in the earth's history. We want to know why that happened. What were those bacteria doing beforehand? What forced them to develop this radically new way of making a living?</p><p>Bacteria don't leave fossils, per se, but they can leave behind metabolic signatures that sedimentary rocks preserve. They impact the rock's elemental composition, and they alter the ratios between heavier and lighter isotopes of certain elements as well. We can work backward from that information to deduce what the bacteria were doing on the ocean floor and in the seawater above it as those sediments were being laid down.</p><p> </p><p><strong>Q: If the earth has had breathable oxygen for billions of years, why should we care where it came from?</strong></p><p>A: There are two really good reasons.</p><p>One has to do with meeting society's energy demands. There's a tremendous effort at Caltech and elsewhere to develop "solar fuels." Can we do better than green plants? If cyanobacteria did the best they could under tight constraints, maybe not. But if there are a variety of ways to do that chemistry, maybe we can clear the slate and do something entirely different.</p><p>The deeper reason is that atmospheric oxygen rewrote life's recipe book. Oxygen-based metabolism provides extra energy that can be invested in cellular specialization. A group of specialized cells can become a tissue, and eventually you have complex creatures with limbs. It's like agriculture—when you start growing crops, you have surplus food. Villages spring up. Craftsmen appear.</p><p>It gets to the Big Question—how rare <em>are</em> we? The earth is 4.5 billion years old, and the oldest evidence for life is about 3.5 billion years old. It took another billion years until photosynthesis, and two billion more for animals to develop. Is it possible to evolve advanced creatures under a different set of constraints leading to completely different metabolisms? If we're looking for life on worlds that play by different rules, will we recognize it?</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: As a small kid, I always loved science. That disappeared somewhere in middle school, so I went to Colorado College in Colorado Springs—a small, liberal-arts school with a really intense curriculum called the block plan. You take one class at a time for a month. You're completely immersed—lecture from nine to twelve, break for lunch, afternoon labs, evening homework. Lather, rinse, repeat. I took a geology class on a whim, because my grandfather had once taught paleontology there. The class vanished into the mountains for a month, and I was hooked.</p><p>In graduate school at Harvard, I worked with Andy Knoll, a Precambrian paleontologist who's trying to understand what the world looked like before animals. Andy's primary appointment is actually in the biology department, and I built on my sedimentary-geology background with a lot of biology classes—molecular biology, biochemistry, genomics, comparative biology, evolutionary biology. And then I came here as an Agouron Postdoctoral Scholar in Geobiology in 2007. I was fortunate that they invited me to stay.</p><p> </p><br /><div><strong style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; "><em style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; ">Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541" style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; color: rgb(0, 116, 189); text-decoration: none; "><strong style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; "><em style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; ">Caltech's iTunes U site</em></strong></a><strong style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; "><em style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; padding-left: 0px; border-top-width: 0px; border-right-width: 0px; border-bottom-width: 0px; border-left-width: 0px; border-style: initial; border-color: initial; vertical-align: baseline; ">.</em></strong></div></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://web.gps.caltech.edu/~wfischer/" class="pr-link">Woody Fischer's website</a></div></div></div>Mon, 17 Nov 2014 17:25:59 +0000dsmith44508 at http://www.caltech.eduQuantum States of Matter in Crystalshttp://www.caltech.edu/news/quantum-states-matter-crystals-44025
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/Hsieh-Watson-Lecture-NEWS-WEB.jpeg?itok=8_GSsVRR" alt="crystal" /><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: iStock</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><em style="line-height: 1.538em;">David Hsieh, an assistant professor of physics at Caltech, is searching for new forms of matter that exhibit weird quantum properties in bulk. Find out the why, where, and how at 8 p.m. on Wednesday, October 15, in Caltech's Beckman Auditorium. Admission is free.</em></p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I'm an experimental condensed-matter physicist. I'm searching for quantum phases of matter in crystals big enough to hold in your hand. A quantum phase occurs when the electrons in a crystal share a quantum state that creates an interdependence among them. This can lead to tangible phenomena that seem to defy the laws of everyday physics. </p><p>The three familiar phases of matter—solids, liquids, gases—are governed by electrostatic forces. Likewise, free electrons interact with one another through electrostatic repulsions. If you just threw a bunch of electrons into a box, they'd eventually situate themselves as far away from one another as possible. These forces are not under our control, but when we embed electrons in a crystal, they swim in a lattice of ions that can facilitate many other types of interactions. By properly choosing those ions, we can actually exert a significant degree of control over the interactions and start creating new forms of quantum matter. My group is particularly interested in two types of interactions: electron-electron repulsion, and spin-orbit coupling.</p><p>Electron-electron repulsions are relatively weak in the metals we typically encounter in daily life. But under the right circumstances, the repulsions can get really, really big, and the material becomes a high-temperature superconductor. "High temperature" in this context means keeping the material at –135°C instead of –245°C, or in other words, keeping them really cold as opposed to really, <em>really</em> cold. Can a room-temperature superconductor be made? Nobody knows.</p><p>The other interaction that interests me is called spin-orbit coupling. Basically, an electron can be either "spin up" or "spin down," and most materials have an equal population of each all swimming around in random directions through the crystal. An atomic nucleus has a positive charge, so it emits an electric field. If the atom is really big and heavy, like lead or bismuth, the field is actually strong enough to torque the spins of passing electrons so that they all leave pointing in the same direction. The importance of spin-orbit coupling was given a huge boost about 10 years ago, when people began to think about so-called "topological order" in crystals. The hallmark of topological objects is that the <em>bulk</em> of that object doesn't carry electricity, but the <em>boundaries</em> carry it almost perfectly. This property cannot be induced in a non-topological system.</p><p> </p><p><strong>Q: What are these quantum phases of matter good for?</strong></p><p>A: If you have something that carries electricity almost perfectly, the most straightforward application is microelectronic circuitry. Integrated circuits are made of semiconductors; the electricity that a semiconductor does not conduct gets dissipated as heat, which is why computer rooms are so heavily air-conditioned. A near-perfect conductor would generate very little heat. It could be a very "green" technology, so if you're running huge server farms, like Amazon.com or Google, the energy savings would be tremendous.</p><p>Moreover, the current would be spin-polarized—all the electrons' spins would point in the same direction—making topological materials ideal for wiring up spintronic circuits. Spintronics is an emerging computer technology that reads and writes information by using electric fields to manipulate spins, or magnetic fields to manipulate charge.</p><p>And if you start to assemble structures from both topological <em>and</em> conventional materials, you may get objects that might be used to build quantum computers.</p><p>I'd like to push further. Nobody knows what happens when you create both spin-orbit interactions <em>and</em> electron-electron interactions in the same crystal. A lot of condensed-matter physicists are going in that direction—it's an experimentally unknown territory.</p><p>We're also looking for what are called topological superconductors. Topological superconductors are predicted to have the potential to perform quantum computations in a fault-tolerant way, meaning that they would resist perturbations from the outside world that would otherwise crash the computer. There's a huge quantum-computing effort going on at Caltech, and engineering fault tolerance into the system is a key element.</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: Well, I wanted to do fundamental physics, but I also hoped to see societal benefits from my research within my lifetime. So I'm idealistic, but there's some pragmatism there, too. When I went to Princeton as a graduate student, I wanted to do experimental tests of string theory. But after a couple of years I grew increasingly attracted to condensed-matter physics, so I changed fields and wound up doing my PhD thesis on topological materials.</p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U site</em></strong></a><strong><em>.</em></strong></p></div></div></div>Mon, 13 Oct 2014 18:24:26 +0000dsmith44025 at http://www.caltech.eduFrom Nature to the Pharmacy: The Chemistry Behind Modern Medicineshttp://www.caltech.edu/news/nature-pharmacy-chemistry-behind-modern-medicines-42741
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/Macrocycle.jpg?itok=MZ3nIN7f" alt="Molecular structure of Nocardioazine A." title="Molecular structure of Nocardioazine A." /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">A new molecule synthesized by the Reisman laboratory en route to synthesizing nocardioazine A, a compound isolated from marine bacteria that reduces chemotherapy resistance in certain cancers. Nitrogen atoms are shown in blue, oxygen in red, carbon in black, and hydrogen in white.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Haoxuan Wang and Larry Henling, Reisman laboratory</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><span style="line-height: 1.538em;">Natural products—molecules originally isolated from bacteria, fungi, plants, and other sources—often have medicinal values that can be enhanced by careful reengineering. For example, an aspirin tablet is a much better pain reducer than an extract of willow bark. Chemistry professor Sarah Reisman's lab develops synthetic methods to help organic chemists tweak existing molecules and even build new ones from scratch. On Wednesday, May 7, she will describe some tools of the trade.</span></p><p>The talk begins at 8:00 p.m. in Caltech's Beckman Auditorium. Admission is free.</p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I'm a synthetic organic chemist. I spend a lot of time thinking about how to make small, carbon-based molecules—roughly the size of steroids, and comparable to most pharmaceuticals—that have some sort of biological activity. We try to prepare them in our laboratory so that through collaborations we can figure out how they work. We're more on the basic-research side of the spectrum; we develop synthetic tools that we, or researchers in pharma, can use to build molecules.</p><p>Natural products are relatively rare compounds. For example, the important antitumor drug Taxol—which we do not work on—was originally isolated from the Pacific yew tree. The yew population would have been decimated if the tree had been used as the commercial source of paclitaxel, which is the generic name for the drug. The manufacturers figured out how to culture an intermediate compound and finish the preparation synthetically, but first the demand for material inspired several chemical syntheses of the natural product.</p><p>Total chemical syntheses of natural products are complicated endeavors, because these molecules have very specific three-dimensional structures. The reactive parts that give the molecule its function all have to be connected in the correct spatial orientation, so how you bring the atoms together is really important. You have to figure out how to selectively engage and modify one part of the molecule without messing up the rest of it. Organic chemists have spent a long time developing these types of selective reactions, which is really what we do in my lab. And despite constant advancement in our understanding of synthetic organic chemistry, it is very much an empirical science. There are all sorts of rules and guidelines, but there are frequently exceptions to the rules and that's where things get interesting.</p><p>Working out the best order to do things is a big part of the challenge. We want to make these molecules in a reasonable way—usually in 20 synthetic steps or less. That's still on the high side, but it's reasonable. It's rare to obtain a 100 percent yield, and 20 synthetic steps with even a 75 percent yield at each step would lead to a very low overall yield. So we look for high-yield transformations wherever possible.</p><p> </p><p><strong>Q: What's exciting about this? What motivates you?</strong></p><p>A: Well, I think it's pretty neat that most of what we make has never been made before. The goal is to make some compound that nature produces, but we get to design new molecules along the way.</p><p>We usually start with the target molecule and work backward—using either known transformations, or our intuition about reactions we might be able to develop—and as we simplify the target, we get to compounds that haven't been made before. Then we ask ourselves, okay, how do we actually make those compounds? And we work our way forward to those checkpoints—again, using known reactions, or new ones that we develop—but now starting from commercially available chemical building blocks.</p><p>I was drawn to organic chemistry because there's a tremendous amount of creativity embedded within it. There is no definitive right way to make a molecule. It's like putting together a jigsaw puzzle where you get to cut your own pieces. You figure out how to break the molecule up, and then how best to reassemble it. It's a lot of fun.</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: When I went to college I wanted to go to medical school. My declared major was biology, because I had heard that that was a good way to get in. Then, as a sophomore, I had to take organic chemistry as part of the premed requirement. I got hooked. It was unlike any other chemistry course I'd ever taken, because it was so creative. After I got into an organic chemistry lab and did some research, there was no looking back.</p><p> </p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U</em></strong></a><strong><em> site.</em></strong></p></div></div></div>Mon, 05 May 2014 16:45:37 +0000dsmith42741 at http://www.caltech.eduSay Hello to Your Little Friends: How Gut Bacteria Can Be Harnessed as Novel Therapies for Diseasehttp://www.caltech.edu/news/say-hello-your-little-friends-how-gut-bacteria-can-be-harnessed-novel-therapies-disease-42424
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/WatsonLecture-Mazmanian2014-NEWS-WEB.jpeg?itok=iAc0KEqF" alt="" /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">This 3-D reconstruction of a mouse colon shows beneficial bacteria (green) interacting with the intestinal surface. The gut cells are rendered in red, and their DNA in blue.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: S. Melanie Lee, Zbigniew Mikulski, Sarkis K. Mazmanian</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><span style="line-height: 1.538em;">On Wednesday, April 2, Professor of Biology <a href="http://www.bbe.caltech.edu/content/sarkis-mazmanian">Sarkis Mazmanian</a> will introduce you to the array of bacteria—your microbiome—residing on your skin, in your mouth, and even deep in your guts. Millions of years of coevolution have inextricably linked you and your microbiome, whose chemical "factories" help keep you healthy by doing such things as synthesizing vitamins and digesting your food. Recently, Mazmanian's laboratory has uncovered the surprising roles they play in fending off certain diseases.</span></p><p>The talk begins at 8:00 p.m. in Caltech's Beckman Auditorium. Admission is free.</p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: Our laboratory studies how beneficial microbes in the gastrointestinal tract interact with the immune and nervous systems. We each carry two to three <em>pounds</em> of bacteria—known as the human microbiome—in our bodies, and we have 10 times more microbial cells than we do human ones. We're outnumbered by an order of magnitude, but our cells are about 1,000 times bigger. Although most of these bacteria reside in our guts, in the colon, their metabolic products are found throughout the body. We think that these molecules can flip switches in biological circuits—even those in our brains. Pasteur knew about the bacteria in our intestines 150 years ago, but the evidence that some are beneficial is less than a decade old.</p><p> </p><p><strong>Q: As President Lyndon Johnson used to say, "How does this help Grandma?"</strong></p><p>A: [laughs] As Sarkis says, "How does this change the world?" It's an entirely new perception. The game-changer is that we have found specific microbes that, at least in animal models, interact with the immune and nervous systems to ameliorate inflammatory bowel disease, multiple sclerosis, and even autism.</p><p>Western civilization has successfully controlled infectious, disease-causing microbes through antibiotics, vaccination, personal hygiene, and sanitation. These approaches are usually indiscriminate, and have also changed our association with microbes as a whole. And if some microbes are actively conferring health on us, say by secreting some substance that helps our immune system function properly, then removing them may result in disease.</p><p>We're all born sterile, and in the first three years of life we develop a complex consortium of microorganisms. Our first exposure is during the birthing process. Children born through natural childbirth are more resistant to allergies and autoimmune diseases than children who are born through C-sections, and the same is true with children who are breast-fed versus formula-fed. We don't yet know where the rest of our microbes come from, but my best guess is human contact. I mean, just think about human contact <em>now</em>, versus a thousand years ago. There's hand sanitizers, soap and water, indoor plumbing . . . We're not recolonizing <em>ourselves</em>, reexposing <em>ourselves</em> to our own microbes, let alone exposing our children to our adult microbes. Throughout human evolution there has been a cycle by which we have inoculated our kids, and I think we've disturbed—or even broken—that cycle.</p><p>We can now begin to think about supplementing or replacing those beneficial organisms, so I don't think it's far-fetched that, within a decade or so, doctors might examine your microbiome as well as looking at your lipid levels and your sugar levels and doing other routine diagnostics. And if they identify an organism that you are missing, you might be prescribed an FDA-approved pill that contains microbes—or microbial products—to restore the benefits you've lost.</p><p>Eating yogurt is not going to do it, nor will playing in the dirt, nor will the probiotics at health-food stores. None of those organisms coevolved with humans, so in essence they just pass through your system. This is a very important point: there's a distinction between the microbes in the environment and the microbes in your gut.</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: As a graduate student, I was studying <em>Staphylococcus aureus</em>, which causes staph infection. Staph infections are a huge problem in the community, and in hospitals, and we discovered some fruitful mechanisms to inhibit staph from causing disease. But as I was thinking about the next phase of my career, I read an article about all these bacteria that live in our gut that nobody was studying. And that interested me, so very, very quickly I decided that I was going to go into the <em>unknown</em>. I was just convinced, in this almost intuitive way, that all these bacteria must either be neutral, and were not doing anything—which is very unlikely, if you understand microbial metabolic processes—or that some subset of them must be doing something beneficial. Otherwise, why would they still be there? So I wanted to study the good guys, and I wanted to do what nobody else was doing. And this is the beauty of Caltech. We do the things here that nobody else is bold enough, or daring enough, to do.</p><p> </p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U</em></strong></a><strong><em> site.</em></strong></p></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://resolver.caltech.edu/CaltechES:72.1.Friends" class="pr-link">"Say Hello to Your Little Friends" by Marcus Y. Woo, Engineering &amp; Science magazine, Spring 2009</a></div><div class="field-item odd"><a href="http://sarkis.caltech.edu/Welcome.html" class="pr-link">Mazmanian Research Group</a></div></div></div>Mon, 31 Mar 2014 19:06:49 +0000dsmith42424 at http://www.caltech.eduWhen Rocks Roll: How Sediment Transport Shapes Planetary Surfaceshttp://www.caltech.edu/news/when-rocks-roll-how-sediment-transport-shapes-planetary-surfaces-42279
<div class="field field-name-field-subtitle field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Watson Lecture Preview</div></div></div><div class="field field-name-news-writer field-type-ds field-label-inline clearfix"><div class="field-label">News Writer:&nbsp;</div><div class="field-items"><div class="field-item even">Douglas Smith</div></div></div><div class="field field-name-field-images field-type-file field-label-hidden"><div class="field-items"><div class="field-item even"><div class="ds-1col file file-image file-image-jpeg view-mode-full_grid_9 clearfix ">
<img src="http://s3-us-west-1.amazonaws.com/www-prod-storage.cloud.caltech.edu/styles/article_photo/s3/WatsonLecture-MLamb-NEWS-WEB.jpg.jpeg?itok=O2OfhQcD" alt="" /><div class="field field-name-field-caption field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">A high-resolution 3-D topographic rendering of the San Gabriel Mountains north of Pasadena, California. The red areas highlight very steep terrain, with slopes in excess of 45 degrees.</div></div></div><div class="field field-name-credit-sane-label field-type-ds field-label-hidden"><div class="field-items"><div class="field-item even">Credit: Roman DiBiase</div></div></div></div></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><span style="line-height: 1.538em;">On Wednesday, March 19, Professor of Geology Michael Lamb will describe how flowing water and grains of sand create Earth's dramatic landscapes. Mars and Saturn's moon Titan show signs of similar processes. Lamb's work on the mechanics of landscape evolution may change how we think about debris flows in the San Gabriel Mountains, the effects of wildfires on erosion, and water on Mars.</span></p><p>The talk begins at 8:00 p.m. in Caltech's Beckman Auditorium. Admission is free.</p><p> </p><p><strong>Q: What do you do?</strong></p><p>A: I'm a geologist. I study the basic mechanics of how sediment moves—how rivers erode rock and form canyons, how sediment builds deltas like the Mississippi's, how landslides work, and so on.</p><p>In the U.S., my field dates back to John Wesley Powell, who led a survey party by boat down the Grand Canyon a few years after the Civil War. For decades, geomorphology consisted of classifying landforms—identifying different types of mountain ranges, or hills, or canyons. Now, we're quantifying the processes that operate at Earth's surface to shape those landforms.</p><p>One challenge, which is true of much of the Earth sciences, is to link these process studies with the evolution of Earth's surface over geologic time. So in addition to field work, my research group has a lab where we make indoor rivers and landslides, and 'speed up time' to observe their dynamics. For example, the Mississippi River jumps to a new course from time to time, and each jump builds a new lobe of the delta. These jumps happen about once every 1,000 years, but by scaling things properly we can speed up the clock and build deltas much faster in the laboratory. We also study rare, catastrophic events, such as megafloods, which would be difficult or dangerous to measure in nature.</p><p>It's an exciting time to be a geomorphologist because we have the opportunity to apply lessons learned on Earth to Mars and Titan—two other planetary bodies with river networks. Titan's surface appears to be active, with rainfall feeding into lakes and rivers with enough force to move gravel and even cobbles, which are roughly tennis- to basketball-sized. Titan is so cold that the "rain" is liquid methane and the "rocks" are water ice, but otherwise the system seems very similar to the water cycle on Earth. On Mars, the river canyons are now dry, probably long dry. In many ways, Mars represents the ultimate inversion problem. With little to go on except for images and topographic data, what can we deduce about the water flows and climate on Mars that led to the formation of these ancient features?</p><p> </p><p><strong>Q: How did you get into this line of work?</strong></p><p>A: I started college at the University of Minnesota in civil engineering. I always was fond of mechanics, and thought that I would likely become an engineer. But I also was fond of the outdoors—natural landscapes and national parks—so I had a desire to connect both interests. I took elective classes in geology and found them to be much more interesting than my engineering classes, so I switched majors. I also had an opportunity as an undergrad to work in the St. Anthony Falls Hydraulics Laboratory at the University of Minnesota, which introduced me to the indoor-analogue river experiments I now do.</p><p>Flume experiments have been used in civil engineering for many decades—for example, if you dam a river, what will the effects be? In fact, what we're doing today is similar in some ways to techniques that were pioneered here at Caltech by Professors Vito Vanoni [BS '26, MS '32, PhD '40], Norm Brooks [PhD '54], and others—first in the Sediment Lab, which was built in 1936, and later in the W. M. Keck Laboratory of Hydraulics and Water Resources. But now we're addressing how the natural world works over geologic time, rather than how the engineered world works over human time.</p><p> </p><p><strong>Q: In light of our recent mudslides, do you have any take-home lessons for the general public?</strong></p><p>A: I have been working on the connection between the wildfires, floods, and debris flows that tend to plague not only Los Angeles but other areas in the southwestern United States, and I will focus my lecture on this topic. For now I'll just say that what you hear in the news about hillsides giving way and causing landslides after wildfires is probably not accurate in many landscapes. Our work shows that there might be a different way to think about the fire-flood problem, especially in very steep and rapidly eroding landscapes like the San Gabriel Mountains.</p><p> </p><p><strong><em>Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at </em></strong><a href="http://itunes.apple.com/us/itunes-u/watson-lectures-sd/id422627541"><strong><em>Caltech's iTunes U</em></strong></a><strong><em> site.</em></strong></p></div></div></div><div class="field field-name-field-pr-links field-type-link-field field-label-above"><div class="field-label">Related Links:&nbsp;</div><div class="field-items"><div class="field-item even"><a href="http://www.caltech.edu/content/rivers-landslides-charting-slopes-sediment-transport" class="pr-link">From Rivers to Landslides: Charting the Slopes of Sediment Transport</a></div><div class="field-item odd"><a href="http://geomorph.caltech.edu/" class="pr-link">Lamb Research Group</a></div><div class="field-item even"><a href="http://calteches.library.caltech.edu/96/1/Vanoni.pdf" class="pr-link">"Sediment Transportation Research" By Vito A. Vanoni, Engineering and Science Monthly, July 1944</a></div></div></div>Thu, 13 Mar 2014 23:17:53 +0000dsmith42279 at http://www.caltech.edu